A NUMERICAL STUDY ON THE UNDERWATER APPARENT CONTACT ANGLE OF OIL DROPLETS ON MICROSTRUCTURE SURFACE

In this study, the apparent contact angles of oil droplets on the rough surfaces in water were numerically studied using the Volume of Fluid (VOF) model. The results showed that the roughness of the surface affected the wettability. By increasing the roughness of the surface, the oleophilicity of the oleophilic surface and the oleophobicity of the oleophobic surface could be increased. Furthermore, the applicability and limitations of the prediction of the underwater apparent contact angle of the oil droplet by the contact angle model were investigated by 3D numerical simulations. It suggests that Wenzel model can accurately predict the underwater apparent contact angle of oil droplets on all the oleophilic, neutral and oleophobic surfaces, and Cassie model can only be applied to the oleophobic surface and Cassie-Baxter model can only be applied to the oleophilic surface.